Primary exercises
- Manually created factor.
In a study participants were asked whether their sport activity is none, oncePerWeek, severalPerWeek or daily.
Build a proper factor for the responses below and store it in a variable w.
Print the factor.
Write the code to count the numbers of occurrences of each level and print the counts.
severalPerWeek, none, none, oncePerWeek, oncePerWeek, oncePerWeek, oncePerWeek, ?, none, none
v <- c( "severalPerWeek", "none", "none", "oncePerWeek", "oncePerWeek", "oncePerWeek", "oncePerWeek", NA, "none", "none" )
w <- factor( v, levels = c( "none", "oncePerWeek", "severalPerWeek", "daily" ) )
w
[1] severalPerWeek none none oncePerWeek oncePerWeek oncePerWeek
[7] oncePerWeek <NA> none none
Levels: none oncePerWeek severalPerWeek daily
fct_count( w )
# A tibble: 5 × 2
f n
<fct> <int>
1 none 4
2 oncePerWeek 4
3 severalPerWeek 1
4 daily 0
5 <NA> 1
- A factor with a random content.
Read help about the function sample.
Then study and try the following lines of code to understand the results.
Next, understand why an error is generated and use replace argument to generate a vector with 100 samples.
Store this vector in a variable v and build a factor w from it.
Finally, count the numbers of occurrences of each level in w.
Ensure, that levels are in order provided in the variable lvs.
lvs <- c( "none", "oncePerWeek", "severalPerWeek", "daily" )
sample( lvs, 3 )
[1] "daily" "oncePerWeek" "severalPerWeek"
sample( lvs, 3 )
[1] "oncePerWeek" "none" "daily"
sample( lvs, 3 )
[1] "oncePerWeek" "none" "daily"
sample( lvs, 100 )
Error in sample.int(length(x), size, replace, prob): cannot take a sample larger than the population when 'replace = FALSE'
v <- sample( lvs, 100, replace = TRUE )
w <- factor( v, levels = lvs )
w
[1] none severalPerWeek oncePerWeek daily daily none
[7] severalPerWeek none none daily oncePerWeek daily
[13] oncePerWeek oncePerWeek none daily daily none
[19] daily oncePerWeek oncePerWeek none daily oncePerWeek
[25] daily none daily none severalPerWeek daily
[31] oncePerWeek none none daily severalPerWeek oncePerWeek
[37] daily oncePerWeek oncePerWeek oncePerWeek oncePerWeek none
[43] none severalPerWeek oncePerWeek oncePerWeek daily severalPerWeek
[49] severalPerWeek severalPerWeek oncePerWeek severalPerWeek oncePerWeek oncePerWeek
[55] oncePerWeek none oncePerWeek daily daily severalPerWeek
[61] oncePerWeek severalPerWeek daily oncePerWeek oncePerWeek daily
[67] severalPerWeek severalPerWeek daily oncePerWeek daily oncePerWeek
[73] oncePerWeek daily severalPerWeek none none oncePerWeek
[79] none daily oncePerWeek oncePerWeek severalPerWeek none
[85] oncePerWeek oncePerWeek none severalPerWeek none oncePerWeek
[91] oncePerWeek daily severalPerWeek daily none daily
[97] daily severalPerWeek none daily
Levels: none oncePerWeek severalPerWeek daily
fct_count( w )
# A tibble: 4 × 2
f n
<fct> <int>
1 none 22
2 oncePerWeek 33
3 severalPerWeek 18
4 daily 27
- Reordering factor levels.
When a factor is shown on an axis of a plot, the order is given by its levels.
The factor w from the previous exercise will be then shown in this order: none, oncePerWeek, severalPerWeek, daily.
But for a picture in a manuscript the following order might be needed: daily, severalPerWeek, oncePerWeek, none.
Apply to w one of the fct_ functions from the tidyverse library to produce a factor w2 with the requested order.
Show the levels of w2.
Again show the number of elements of each level in w2 and compare it with the table of the previous exercise.
w2 <- fct_relevel( w, c( "daily", "severalPerWeek", "oncePerWeek", "none" ) )
levels( w2 )
[1] "daily" "severalPerWeek" "oncePerWeek" "none"
fct_count( w2 )
# A tibble: 4 × 2
f n
<fct> <int>
1 daily 27
2 severalPerWeek 18
3 oncePerWeek 33
4 none 22